1. Field of the Invention
The present invention relates to a manufacturing process of a diesel gas oil with a high cetane number and a low sulfur. More particularly, the present invention relates to a manufacturing process of a diesel gas oil with a high cetane number, a low sulfur content, and a superior storage stability from a petroleum distillate oil with a low cetane number and a high sulfur content.
2. Background Art
Presently, diesel gas oil used in Japan is prepared by mixing a straight-run gas oil cut, a straight-run kerosene cut, a gas oil cut obtained from a cracking apparatus, or the like, with a desufurized gas oil cut which is obtained mainly by treating a straight-run gas oil with a general desulfurization apparatus. Considering that a clean oil will be required much more in the future, it is expected that in the diesel gas oil a content ratio of the gas oil cut obtained from the cracking apparatus will increase more and more. However, since the gas oil cut obtained from a fluid catalytic cracking (FCC) apparatus or a thermal cracking apparatus contains a lot of aromatic components, the cetane number thereof is low as it is. Additionally, the sulfur content thereof is usually at least 500 ppm, and there is not any less than 350 ppm. Furthermore, when the gas oil cut is hydrogenated, unstable substances are generated and the storage stability (hue and sludge amount) gets worse.